SBIR-STTR Award

The discovery of large-scale coherent structures and their recent Emphasis in research introduces the notion that turbulent shear and a boundary layer flows consist of quasi-deterministic structure and the transport and entrainment are mostly induction driven rather than due to gradient diffusion. Turbulence control such as suppression of turbulence and drag reduction, jet noise production and broadband noise amplification are a few important applications which demand thorough understanding of the physics. The primary specific objective of this phase I effort will be to determine the most effective and efficient approaches to generate or reinforce large-scale, periodic structures in turbulent shear and boundary layer flows. A secondary objective will be to investigate ways to also shift the turbulent dynamic energy to reduce the intensity of the background small-scale or isotropic turbulence. Accomplishing these objectives will allow turbulent flows to be: manipulated in order to reduce optical aberrations due to scattering by removing low order zernike terms with state-of-the-art adaptive optics correction systems.

The discovery of large-scale, coherent structures, their recent emphasis in research, and their influence on turbulent flow control make them an important subject for research. Current applications demand thorough understanding of the physics. With the advent of adaptive optics correction systems, one can reduce optical aberrations due to relatively low frequency jitter as expressed by low order zernike polynomials (such as piston, tilt, coma, etc.). For these reasons, it is readily apparent that one should 1) stimulate and reinforce the large-scale, coherent structure at the lower frequencies in the turbulent flow through which the signal propagates; 2) remove the corresponding optical degradations by incorporating a suitable adaptive optical correction scheme; and, 3) simultaneously reduce the high frequency, scattering aberrations. This phase II research will address approaches to accomplish just these goals.